I host several domains on my server, including dpotter.net.  Recently I added another domain for a friend who is starting her own business.  I thought I remembered all the steps to provide both web site service and email service, but there was one I missed that I don’t remember being a requirement before.

For background, I’m running Microsoft Small Business Server 2003 with IIS 6 and Exchange Server 2003.  My box is also a domain controller, a DHCP server, a DNS server, an RRAS server, and a few other servers to boot.

First let me describe what I ran into and then I’ll list the steps I use to add a domain.  I added the domain so that Exchange could recognize it, added a user with a mailbox for my friend, and set up my spam filter (Exchange Hosted Services, aka Frontbridge) to allow traffic to the new domain to pass through it successfully.  However, whenever I tried to send email to the new user from an outside mailbox, I would get the following non-delivery report:

Unable to relay for (in reply to RCPT TO command)

After much hair-pulling and Internet searching, I ran across an article titled Multiple Email Domains on Exchange 2K3 - Relay Access Denied by James Montgomery.  It spelled out the extra step I had to take - update the IIS Metabase.  Huh?  I’d never had to do that before.  But it worked, so I’m a happy camper again.

Note that to modify the IIS Metabase you’ll have to download and install the IIS 6 Resource Kit.

Adding a domain
  1. Add the domain to Active Directory as a UPN suffix.  This will allow you to add users that can log in using the new domain.
    1. Run the Active Directory Domains and Trusts management tool from Administrative Tools (domain.msc).
    2. View properties of the root node in the console (titled Active Directory Domains and Trusts).
    3. Add the new domain and click the Add button.
  2. Add a new domain to the set of Internet message formats in Exchange System Manager.
    1. Run the Exchange System Manager tool from Administrative Tools.
    2. Open Global Settings.
    3. Right-click on Internet Message Formats, click New, then click Domain.
    4. Type the name of the domain in both the Name and SMTP domain fields.
    5. Click OK.
  3. Add a recipient policy for the new domain.
    1. Run the Exchange System Manager tool from Administrative Tools.
    2. Open Recipients.
    3. Right-click on Recipient Policies, click New, then click Recipient Policy.
    4. Select E-Mail Addresses and click OK.
    5. Type the name of the new domain in the Name field.
    6. Switch to the E-Mail Addresses (Policy) tab.
    7. Create a new smtp policy for the new domain.
      1. Click New and select SMTP Address.
      2. Type the name of the new domain with an at-sign before it (e.g. @mydomain.com) and click OK.
  4. Add the domain to the IIS Metabase.
    1. You may want to perform a backup of your metabase before proceeding.
    2. Open MBExplorer from the IIS 5 Resource Kit.
    3. Navigate to LM\SmtpSvc\1\Domain\.
    4. If the new domain is not in the list (which is probably will not be), add a key for the new domain.
      1. Right-click one of the other domains and click Copy.
      2. Right-click Domain and click Paste.
      3. Select Copy to a new key.
      4. Type the new domain name and click OK.
    5. Run the iisreset tool to reset IIS (click Start » Run, type iisreset, and press Enter).

Now you can create users that use the new domain in Active Directory Users and Computers and you can create web sites that use the new domain in IIS Manager.